wifi not working..

on my dell laptop not even 4 months old my wifi is being weird... when i start the computer up the little wifi LED comes on indicating that theres wifi near, so i click on windows wifi manager and it shows me all the available networks, but it wont connect to any of them, not even my preferred ones. Could i have disabled something?

i dont really know what i did, i just kept messing with it and eventually it worked... its odd because it didnt work in xp or vista, then i messed with it a little (uninstalling/installing drivers) and it seems to connect in xp fine now, i havent tried vista again.